Chennai Metropolitan Water Supply and Sewerage Board
Advanced Water Treatment Technologies – Chennai Initiatives Workshop conducted by MoUD, New Delhi 11.03.2011 WATER TREATMENT TECHNOLOGIES ADOPTED
Conventional Water Treatment 270 MLD WTP at Kilpauk (1914 – Slow sand Filters 60 MLD) / (1959 – Rapid sand filters 45 MLD) / (1973 – Rapid sand filters 135 MLD) / (1990 – Rapid sand filters 90 MLD) 300 MLD WTP at Puzhal (1996) 180 MLD WTP at Vadakuthu (2004) Pulsator Technology based Water Treatment 530 MLD WTP at Chembarambakkam (2007) Brackish water (R.O. based) Water Treatment Sea water Desalination 100 MLD Plant at Kattupalli, Minjur (2010) 100 MLD Plant at Nemmeli – Ongoing and completed by 2012 Sewage Renovation (TT / RO based) for Industrial use Collaboration with Industries (CPCL / MFL / GMR Vasavi) – 41 MLD NEED TO GO IN FOR LATEST WATER TREATMENT TECHNOLOGIES
Slow sand filters occupies more space – limitations in expansion Low filtration rates – limitations in meeting the demands Replacement of media due to clogging / Time consuming Danger of flooding during Monsoon due to open to air construction WATER TREATMENT PLANT AT RED HILLS ( BOT) - 1996
Capacity 300 MLD
Work completed & 1996 Commissioned
Cost Rs.50.43 Crore
The Operation & Maintenance of the Plant is done by Private Contractor except the major repairs and replacement which are being carried out by the Board 300 MLD WATER TREATMENT PLANT AT PUZHAL - PROCESS FLOW CHART 300 MLD Water Treatment Plant at Puzhal
• Year of Construction - 1996
• Capacity - 300 MLD
• Operation & Maintenance - M/s VA Tech Wabag Ltd
• Period of contract - 3 Years
• Date of commencement - 16.12.2007
• Contract Value - Rs 7,37,55,068/- for 3 years. NEW VEERANAM PROJECT INFRASTRUCTRES -2004
• Raw water pumping, Treatment Plant, Treated water pumping, 228 km pipeline and WDS • Capacity - 180 MLD . Work completed & commissioned - 2004 • Project Cost - Rs. 720 Cr.
After the completion of the construction and commissioning the same contractor are entrusted with O&M including all major repairs and replacements for 5 years 180 MLD WATER TREATMENT PLANT AT VADAKUTHU - PROCESS FLOW CHART 180 MLD Water Treatment Plant at Vadakuthhu
• Year of Construction - 2004
• Capacity - 180 MLD
• Operation & Maintenance - M/s. TMP Manoharan & Co - M/s. VA Tech Wabag Ltd – 2 Packages - M/s. IVRCL Ltd – 2 Packages
• Period of contract - 5 Years
• Date of commencement - 08.09.2010
• Contract Value - Rs 23.11 Crore for 5 years. 530 MLD CHEMBARAMBAKKAM WATER TREATMENT PLANT TREATMENT PROCESS
O&M Cost = Rs.45 Crore for 7 yrs
Total Cost Rs.134.9 Crore (French Assistance = Rs.33.5 Crore + CMWSSB Rs.107.0 Crore
Vacuum Air inlet Valve closed blower
High level THE PULSATOR TECHNOLOGY
Low level water surface
clarification area
Top surface sludge blanket
Sludge blanket Raw waterwater with downward + Raw motion Aluminiumwater + Sludge sulphatesulphateAlum concentrator sulphate
sludge draw down pipe to sludge channel Small raw water flow rate at lateral distribution pipe baffle plates
ADVANTAGES OF PULSATOR TECHNOLOGY
Low chemical consumption
Low water losses on sludge extraction
Low power consumption Low maintenance Low operator input Excellent treated water quality - SS (Low load on filters) - Colloids - Algae ADVANTAGES OF AQUAZUR FILTERS
INLET CHANNEL High Rate Gravity Sand Filters More filtering capacity False Floor Fitted with Nozzles Effective floor usage Uniform Sand media for filtration In-depth clogging longer filtration cycle FILTRATION Constant Head & Constant Rate Filtration MODE Better filter operation Washing - Simultaneous Air & Water Scour
Effective cleaning of bed with less water BACKWASH Washing - Simultaneous Air & Water Scour MODE
SCOUR AIR
B/W OUTLET
B/W WATER BRACKISH WATER R.O. DESALINATION PLANT Metro water has taken a considered decision to focus on Fishermen's Colonies and economically disadvantaged section to supply them with good quality water for drinking and cooking purposes. Since most of them are located close to the sea and in the tail end of the city water supply distribution system, they suffer from lack of potable water, resulting in major health related problems.
A conscious decision was taken to locate a battery of Reverse Osmosis Plants to help these groups by supplying the potable water by treating locally available brackish ground water through Reverse Osmosis Process.
There are three Reverse Osmosis Plants located one at Velachery (4.5 lakhs litres capacity) and the others at Nochikuppam (1.5 lakh litres capacity) and Kasimedu (1.5 lakh litres capacity).
During the year 2001 drought, two new Reverse Osmosis Plants were installed one at Ayothiakuppam (1.00 lakh litre capacity) and another at Kasimedukuppam (Royapuram) serving a population of about 5000 at each location. The Reverse Osmosis Plants consists of open wells and Bore wells to draw the required brackish water for treatment through the Reverse Osmosis Plant.
The raw water drawn from the wells is stored in the storage tanks and pumped to the Dual Media filters consisting of quartz sand and anthracite wherein suspended particles is removed.
The filtered water from the Dual Media filter is pumped to a micron filter to remove the micron size particles and then fed into the Reverse Osmosis Process Unit by means of high pressure pumps. The Reverse Osmosis process module consists of a thin film composite of polyamide membrane. When brackish water is pumped with high pressure through this membrane, the dissolved solids are removed and the output water is of potable quality with dissolved solids content below 500 ppm.
The rejects from the Reverse Osmosis modules with high salt content is put into the nearby sewer system for disposal since the quality is within the permissible limit to dispose through the domestic sewer.
INSIDE VIEW OF R.O.PLANT VIEW OF R.O.PLANT SEA WATER DESALINATION Need for Alternate Non-Rain dependent Sources (Sea water Desalination Project)
Even after implementation of the various water supply augmentation projects and water conservation measures, there is still a shortfall in meeting the water demand of Chennai City and adjoining areas.
Further all the existing sources are depend on monsoon and subject to change in weather patterns and not 100% reliable and assured supply.
Hence, it is necessary to examine the possibility of identifying another reliable and assured source of water supply to bridge the gap between demand and availability. Chennai - Sea water Desalination Project - Contd.,
Govt.of Tamil Nadu is determined to implement a combination of schemes to make available Sufficient quantity of water during normal years Minimum lifeline supply during Critical drought years Govt.of Tamil Nadu has therefore decided to implement two Desalination Plants of 100 MLD capacity each This will ensure lifeline water supply to the residents of Chennai during drought years TECHNICAL ASPECTS OF THE PROJECT
Project Setting up of 100 MLD Seawater Plant on DBOOT basis at Kattupalli, Minjur Terms Bulk Water Purchase Agreement dated 13.09.2005 Operations Period 25 Years
Desalination Process Reverse Osmosis (RO)
Conversion rate of drinking 45% water from sea water No.of RO trains 5
No.of Pressure Vessels 248 in each RO train
Number of Membranes 7 in each pressure vessels
Type of Membrane Composite polyamide spiral wound membranes TECHNICAL ASPECTS OF THE PROJECT
Pre-treatment Coagulation & Flocculation; Clarifier; 2-stage media Filtration Pressure Filtration & Cartridge Filtration Energy Recovery System Energy Recovery System using the principle of positive displacement and isobaric chambers Product Water Quality As per IS 10500 : 1991
SEAWATER INTAKE TRAVELLING SCREEN & FLUSHING PUMPS
• The raw sea water is drawn by gravity from an intake tower erected at 635 m away from the shoreline. • High Density Poly Ethlene (HDPE) pipeline of 1600 mm dia is laid on the seabed for the drawal of 237 MLD raw seawater. • Bar screens and dual flow travelling band screens installed in the seawater sump protect the pumps . • Seawater from the sump is pumped to Pre-treatment Units Chemical Dosing unit for Pre-Treatment
1. Sulphuric Acid is added to decrease pH of sea water in order to maxmize the coagulation 2. Ferric Chroride is added to enhance coagulation of seawater required in the plant. 3. Sodium Hypo chlorite solution is added to disinfect seawater. Pre-treatment – Flocculation Chamber
• The seawater from seawater pump house is pumped to the first pretreatment system namely, flocculation chamber. • Here the suspended, dissolved and colloidal are removed by means of adding chemicals thereby increasing the efficiency of decantation. • Volume to be treated – 237 MLD • Average volume per hour – 9,921 cum/hr. Pre-treatment - Gravity Settlers
• The flocculated water is uniformly distributed in the Gravity Settlers. • The Gravity Settlers have been designed with 4 lamellar decanters with pulsating mire beds with a capacity to treat 237 MLD. • The GRP lamella plates are installed with 60 degrees of inclination, each vase contains 52 lamella plates Intermediate Pumping Station
• The filtered water from the Dual Media Filters is pumped from the intermediate sump cum pump house for the next stage of pressure filtration to obtain clear seawater. • Discharge – 945 cm/hr Pressure Filter Vessels
• The water pumped from the intermediate sump cum pump house is passed through pressure filters to improve the clarity of the seawater • No.of Pressure Filters - 16 Cartridge Filters
• This is the last stage of pre-treatment by which the ultra fine particles, present in the filtered seawater are removed. • There are 10 No.of Cartridge Filters. Reverse Osmosis Process Unit with pressure vessels
• Reverse Osmosis is diffusive mechanism wherein the feed water is highly pressurized using High Pressure pumps before passing through a sequence of membranes placed in a Pressure Vessel, to obtain permeate water or desalinated water. • The water is pressurized to 58 Bar pressure. • The plant has a set of 5 Reverse Osmosis modules each producing 20 MLD of desalinated water. Energy Recovery System
• The pressure in the reject brine water system is nearly 56 Bar. • The pressure energy in the reject brine water is recovered at the outlet of the membrane by means of pressure exchangers. • The high pressure brine exchanges pressure with the pre-treated feed water in the energy recovery system and equally pressurized with Booster Pumps before combining with the feed water from high pressure pumps for the desalination process. • The energy (Power) requirement is reduced by nearly 82% Post Treatment Units
• The desalinate water flowing out of the Reverse Osmosis process unit is rematerialized and pH correction is carried out by adding chemicals such as lime, Carbon-di-oxide and Sodium hypo chlorite solution Product Water Tank
• After the post treatment the product water is collected in a 20 Million litres capacity Underground Tank. • Under ground Tank water is supplied by the company to the CMWSS Board for transmission and distribution to Chennai City 100 MLD DESALINATION PLANT - NEMMELI – Mass flow diagram Location of the plant at Nemmeli 100 MLD DESALINATION PLANT AT NEMMELI
Sl. Name of work Name of the Construction O & M cost Contract Period No contractor Cost for 7 years (Rs. in Crore) (Rs. in Crore) M/s V.A.Tech Construction Wabag Limited of 100 mld in consortium 1 capacity 533.38 500.29 24 Months with M/s IDE Desalination Technologies, Plant Israel. 2 PMC for Plant M/s Mecon Limited in Consortium 13.46 - 24 Months with M/s ADECO Technologies Ltd/SOECO M/s Larsen & Conveyance 3 Toubro Limited 121.47 1.02 20 Months System
REASONS OF ADOPTING ULTRA FILTRATION FOR TSS REMOVAL IN NEMMELI DESALINATION PLANT
Occupies less land area (From 40 Acres at Kattupalli and 19 Acres at Nemmeli
Enhances R.O.Membrane life from 3 to 5 years at Kattupalli and 5 to 7 years at Nemmeli
Ultra filtration is used for most of the plants commissioned for the last 5 Years SEWAGE RENOVATION FOR INDUSTRIAL USE SEWAGE TREATMENT PLANT – ACTIVATED SLUDGE PROCESS FLOW DIAGRAM
1. PRIMARY AND SECONDARY TREATMENT
BOD5 = 350 mg/l Return Sludge TSS = 400 mg/l Screening Grit A Feacal coliform = 4.6 x 106 Parshall flume MPN/100 ML Aeration Inlet Screen Grit Primary Tank chamber chamber chamber clarifier
Raw Sludge Balancing tank Secondary Chlorine contact tank clarifier
Treated Sewage B LEGEND Discharge in Excess Return Primary Treatment Coovam river Sludge
BOD5 = <20 mg/l Biological treatment - TSS = <30 mg/l chlorination Faecal coliform = <10000 C MPN/100 ML SLUDGE TREATMENT AND POWER GENERATION
B 2. SLUDGE TREATMENT Raw Sludge C Excess Return Sludge
Return to A Primary Supernatant Supernatant Centrate clarifier
SLUDGE CENTRIFUGE Sludge for THICKENER DIGESTER Disposal
Bio-Gas SCRUBBER Methane GAS GAS UNIT ENGINE HOLDER LEGEND For Power Generation Power For Sludge treatment Excess Bio- Gas plant Gas Power generation Burner 48 TERTIARY TREATMENT PLANTS INSTALLED BY CPCL AT MANALI SEWAGE RECLAMATION PLANT-1 (capacity: 475 Cu.M/Hr)
• Installed with old lime process by M/s. Hindustan Dorr Oliver in 1991-92 and debottlenecking with UF system was done by Ms. Doshi Ion Exchange Limited in 2004-05.
• Consists four RO banks with each 110Cu.M/Hr feed (3 banks operation and one standby) Sewage Reclamation Plant - I (SRP-I)
Secondary FeCl3 & Anionic treated sewage Chlorine Poly dosing
3.0MGR Surface Clarifiers Intermediate Hydro- Aeration storage treater Tanks pond Refinery / Canteen Sewage
Ultra- Multimedia Pressure Filtration filter sand filter
1.5 MGR for CT makeup Chemical dosing SBS,HCl,Antiscalant Permeate UF Product Cartridge Reverse Degasser Old permeate tank filter Osmosis tank (PT-1)
Reject
Cooling Tower make-up or Rejects to RORR DM Plant Additional RO feed ZDPII SEWAGE RECLAMATION PLANT-2 (capacity: 475 Cu.M/Hr)
• Installed with state of the art technology of Sequential Batch Reactor (SBR) by M/s. VA Tech WABAG in the year 2006-07.
• Consists four RO banks with each 110Cu.M/Hr feed (all four continuous operation) & Reverse Osmosis Reject Recovery (RORR) two banks each with 40 Cu.M/Hr feed Sewage Reclamation Plant - II (SRP-II)
FeCl3 & Anionic Secondary treated Poly dosing sewage
Sequencing Flash High Rate Pressure 2.5MGR Batch Mixer Clarifier sand & Reactor Multi grade Chemical dosing filter SBS,HCl,Antiscallant Ultra- Degasser Reverse Cartridge Break point Osmosis Filtration filter chlorination
Reject Permeate
New permeate Reverse tank (PT-2) Osmosis Final Reject to MPL-II Reject Recovery
DM Plant SEQUENCE OF SEWAGE TREATMENT PLANT
Sewage receipt (Equalisation)
Boilogical treatment (BOD /COD & Ammonia reduction)
Chemical treatment (Coagulation & Flocculation)
Filtration (SS & NTU reduction)
Ultra filtration (removal of colloidal of size 0.01microns)
Chemicals
Cartridge Filtration ( Removal of chemical and other dusts of size upto 10 microns)
Reverse Osmosis (Removal of dissolved particles of size 0.0001microns)
Storage / Export to Refinery BIOLOGICAL TREATMENT
• Aerator : Continuous growth of MLSS (Living micro organism) and diffusion of oxygen. The micro organism consumes organic and inorganic load in feed water. (Results in BOD & COD reduction and also ammonia reduction through nitrification).
• Clarifier: The sludge ( MLSS ) is settled. Ammonia removed through denitrification. (Note : Sequential batch reactor combines both the operation in a single unit in SRP-2)
CHEMICAL TREATMENT
• Hydro Treater High rate clarifier : coagulation of suspended particles and phosphates by addtion of ferric chloride and flocculation by addition of anionic poly electrolyte • Chlorination Break point chloriantion: Disinfection of bacteria and removal of residual ammonia by conversion to chloroamines
FILTRATION • Pressure Sand / Multimedia Multi grade filters : Removal of particle size upto 0.45 microns and iron thereby reducing Suspended Solids (SS) & Trubidity (NTU). • Pressure sand filters loaded with grades of pebbles , coarse and fine sand • Multimedia filters have additional layer of Anthracite for polishing CARTRIDGE FILTRATION
• Removal of chemical dust due to addition of Hydrochloric acid, Sodium Bi sulphite and Antiscalants and dust from feed tanks (up to particle size 10 microns) • The cartridge filter is of spiral wound and thread type and the thread made of Poly propylene or polyethylene material. ULTRA FILTRATION
• Removal of colloidal particles up to 0.01 nm size thereby reducing the Silt Density Index (SDI) of RO feed water.
• The Ultra filtration membranes are made up of Polysulfones material
• In SRP-1 alone the UF is of Cross flow filtration type (with reject) and in all other units of Dead end filtration (without reject) COST FOR DIFFERENT SOURCE WATER
Sl. Source of water Cost per Kilo litres No in Rs. 1 Surface Water (KPS – 270 MLD) 5.48/-
2 Surface Water (Red Hills – 300 MLD) 4.78/-
3 Surface Water (Veeranam – 180 MLD) 10.50/-
4 Surface Water (Chembarambakkam- 530 MLD) 8.04/-
5 Surface Water (Surapet – 14 MLD) 5.11/-
6 Ground Water (Well Fields – 15 MLD) 28.72/-
7 Desal Water (100 MLD) - DBOOT 48.66/-
8 Desal Water (100 MLD) – EPC 20.64/- (To be on stream by 2012) * Total Water Treatment Capacity available = 1400 MLD